1. Field of the Invention
The present invention relates to a semiconductor device and a method of manufacturing the same. More particularly, the present invention relates to a thin film transistor (TFT) and a method of manufacturing the same.
2. Description of the Related Art
In a typical TFT used as a switching device for a flat display, e.g., an LCD or an OLED, the channel is formed of amorphous silicon or polycrystalline silicon. When a channel region of a TFT is formed of amorphous silicon, uniformity may be increased, but high speed operation may be difficult due to low carrier mobility. When the channel region is formed of polycrystalline silicon, carrier mobility may be increased as compared to amorphous silicon, but the reduction of the size of the device may be limited by the grain size of the polycrystalline silicon.
A TFT may be formed on a substrate such as a glass substrate or a sapphire substrate. However, using a glass substrate may make it difficult obtain uniform results. Further, the use of a sapphire substrate may result in reduced carrier mobility, as it is difficult to obtain mobility equal to that achieved a system in which there is no compression stress, or tensile stress is applied, since the channel region of a conventional TFT on a sapphire substrate is under a compression stress.